For my build, 76 912, I’m following the Colin Chapman philosophy of light and simple, so I’m going with a built (cams, STi crank and rods, ITBs) normally aspirated Subaru 2.5, at around 215 hp. This motor is actually lighter than the original VW Type4 that was in there.
Anyways, lighter, smaller motor let’s me run smaller radiators. I worked out the math, and came up with about 200 square inches of radiator frontal area is about the minimum.
So what I’m doing is I’m fitting a pair of Austin Mini radiators (106 square inches per side) under the headlights, and making a complete fiberglass ducts for them. These ducts will have a 12” fan on the back side, and exit into the low pressure area directly under the car. The ducts will basically form an expansion chamber on the front, that increases the static pressure of the incoming air stream. It’s based on the Porsche 996 design.
I spent a lot of time looking up radiator sizes, and the Mini rads fit about the best, all I really have to do is modify the end tanks and re-locate the water lines.
I estimating that this will just about enough, and as a plan-b, there’s more room on the right, so could take a Chevy impala radiator, saw it in half, weld up the end tanks and that will give another 60 square inches.
I’m using a modified 964 bumper (I like the cleaner rounder lines if it), and this forms the front part of the ducts.
I need to put together a video of the design.
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